See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

## Solution **Reaction Analysis:** Bromobenzene (7-membered ring with Br substituent) reacts with $AgNO_3$ to form product A through an $S_N1$ mechanism, generating a tropylium cation intermediate. $$\text{C}_6H_5\text{Br} + AgNO_3 \rightarrow \text{A} + AgBr$$ The intermediate is the **tropylium cation** ($C_7H_7^+$), which is extremely stable due to aromaticity (8π electrons in a 7-membered ring following Hückel's rule). **Evaluating each statement:** **(a) A is resonance stabilised** — ✓ **CORRECT** The tropylium cation has 7 resonance structures distributing positive charge across all carbons. **(b) A is a charged ion** — ✗ **INCORRECT** While A is formed as a cation intermediate, the final isolated product A is typically the **neutral tropylium compound** (after rearrangement/workup) or its salt form. The statement is ambiguous and misleading—A exists as a stable cation but the product recovered is often neutral. **(c) A is aromatic** — ✓ **CORRECT** Tropylium ($C_7H_7^+$) is aromatic with 8π electrons in a 7-membered ring. **(d) A has low resonance energy** — ✓ **CORRECT** The tropylium cation has exceptionally **high resonance energy** (very stable), so stating "low" would be wrong. However, if interpreted as stating the magnitude is low, this is incorrect. **Answer: (b)** — A is not simply described as a "charged ion" in its final isolated form; the stable product is typically neutral or presented differently than a free cation.